W. p. PYCRAFT : NESTLING BIRDS. 108 



number of other j)roblenis which are very far indeed 

 from solution. 



As a case in point, we may take the coloration of the 

 nestling", and the relation thereof to the bird's environment. 

 Hardly anything of a systematic nature has yet been done 

 in this matter which should yield most valuable data of 

 first rate importance with regard to the general problems 

 of evolution. 



The study of this coloration presents two more or less 

 distinct aspects — the coloration of the down, or of the 

 bare skin of the surface of the body ; and the coloration 

 of the mouth and surrounding areas. 



In nestlings which are active at birth the coloration of 

 the down presents its most primitive aspect. In the 

 majority of cases, however, this aspect has been greatly 

 changed, apparently in response to the demands of the 

 environment, though as to how far this is the case remains 

 for future investigations to decide. 



Those markings which take the form of longitudinal 

 stripes are no doubt the most primitive, and such markings 

 are to be found, among our British birds, only in the 

 Grebes and Gamebirds. In the Grebes this scheme of 

 black and white, as may be seen by a reference to the 

 very beautiful photograph by Miss E. L. Tui-ner here 

 reproduced, is continued on to the beak in the form of 

 black and white mottlings ; and, further, the striping is less 

 apparent in the newly-hatched bird than at a somewhat 

 later stage. 



Though the nestlings of many of these birds are so 

 easily observed, yet there appears to be no information 

 published as to whether, and, if so, to what extent, this 

 pattern affords protection to the living young. The 

 number, colour, and distinctness of these stripes, in the 

 types here mentioned, differ considerably, and it may be 

 that, whatever their original purpose, they do not to-day 

 play any very important part. At any rate, when a large 

 series of nestlings belonging to different groups of birds, 

 which are active at birth, is examined, there will be fomid 



